In a mobile communication system using a TDMA (Time Division Multiple Access) cellular process, a microcell mobile communication system has been examined to use frequencies efficiently. A basic zone arrangement used in the microcell mobile communication system includes the arrangement of a service zone by contiguous microcells each having a radius of about 50 to several hundred meters. Another idea has been proposed to form a service zone by very small cells called picocells which are smaller than the microcell. This system includes contiguous very small cells, each having a radius of about 10-50 meters set in offices, in an underground street or a building where the propagation of radio waves is relatively difficult. Further, an idea of a so-called third generation mobile communication system has been proposed to unify both techniques for very small cells and the macrocells realized in a conventional mobile telephone system.
One of the third generation systems includes a FPLMTS (Future Public Land Mobile Telecommunication Systems), the study of which has started internationally. The FPLMTS uses a variety of cell structures such as macrocells, microcells, and picocells arranged in a multilayered (or complex-cellular) structure in a service zone. Thus, high degree radio channel mobile control is indispensable which includes a control of zone switching between the respective cells, and allocation and switching of frequency bands among the respective cells. As the size of the cells becomes very small, problems occur which include an increase of the positional variation of the level of the receiving signal, an increase of the frequency in channel switching (frequency or time slot) during communication, and an increase of the installation cost of the base stations. Further problem is to deal with traffic concentration or jam and provide flexible service for mobile objects moving at very high or very low speeds.
Conventionally, in order to solve those problems, a study has been made of the decentralized autonomous control technique where each base station autonomously determines and uses an available channel, and the dynamic channel allocation which dynamically uses a frequency in accordance with time-dependent and positional variation of the traffic. In particular, in the switching control of a radio channel under communication ("handover"), studies have been made of a system for synchronizing various timing operations between the base stations, high-speed switching frequency synthesizer, etc., in order to cope with an increase in the switching frequency. (See H. Furukawa and Y. Akaiwa "Self-Organized Reuse Partitioning (SORP), A Distributed Dynamic Channel Assignment Method" Technical Report of IEICE. A.-P92-116, RCS92-126 1993-01, pp. 61-66) In those proposed measures, the detection of the moving speed and moving direction of a mobile object is especially important. However, no practical detecting means have been proposed.
A conventional method of detecting the moving speed of a mobile object in a mobile object communication system includes presumption of a Doppler frequency, using indirect measurement. For example, as described in papers B-400 and B-401 published at the 1993-Spring Meeting of Institute of Electronics, Information and Communication Engineers of Japan, the speed of a mobile object is presumed on the basis of the number of times of intersection of power level in an envelope under Rayleigh fading and the measured values of the frequency of switching branches in the reception diversity. This is based on the principle that the number of times of intersection of the power level and the frequency of switching the branches are found statistically to be proportional to the Doppler frequency. Since the results of those measurements and presumptions are indirectly obtained, however, they involve large errors and are not sufficiently satisfactory. In addition, those are applied solely to the detection of the speed of movement of a mobile object.
Another application of the Doppler effect to the mobile communication is intended to compensate for an undesirable frequency shift of the communication wave due to the movement of the mobile object to ensure stabilized communication, as disclosed in Japanese Patents JP-A-58-225741, 63-199527, 5-22183 and 5-37438. Other applications are VICSs (Vehicle Information and Communication Systems) where the communication system receives information on the position and speed, etc., of a car, GPS (Global Positioning System) which use satellites as a global position measuring system, which are, however, large-scaled and complicated.
A location detection system for a mobile terminal which is considered an application of a so-called enterprise cordless telephone locates the mobile terminal on the basis of the intensity of radio wave which has been transmitted through not only the same floor of a building but also a floor or ceiling of the building. Thus, in order to presume a fixed radio base station in the vicinity of which the mobile terminal under detection exists, various devices such as provision of additional devices on passageways and stairs are required in each of the service zones, as described in a paper entitled "A Study of Location Detection System" by Ito, RCS Research Association, Institute of Electronics, Information and Communication Engineers of Japan, RCS 90-48.
The basic concept of the above conventional counter method is to flexibly handle the move of a mobile object or the generation of a new call on the network side or user side. However, this method has an essential weak point. In order to appropriately handle the move of the mobile object, it is indispensable to detect the position of the object and its moving speed and direction substantially simultaneously like in the automatic control of a robot. Nevertheless, this conventional method only presumes the position of the mobile object by causing each of the base stations around the mobile object to monitor and measure the intensity of radio wave on the basis of communication between the base station and the mobile object.
Since the intensity of the radio wave changes depending on place, time and space, it is difficult to improve the accuracy of detection even if a statistical technique is used. This implies that no appropriate detection method has been proposed so far. Thus, there is naturally a limitation in the accuracy of detection, by measurements including flexible network control which has been considered as a method of solving this problem. The Doppler effect, mentioned above, is solely applied to indirect detection of frequency shift and detection of the moving speed of the mobile object. Simultaneous detection of the position of the mobile object and its moving speed and direction and a mobile communication system using the simultaneous detection have not been proposed.